Melt 1 tbsp. of butter in a pan with a heavy bottom, put finely chopped onion and, stirring, fry on a low heat until golden brown for 15 minutes. Pour 1.5 liters of cold water into the saucepan with onion, put the bay leaf, bring to the boil on a medium heat and cook for 10 minutes (the bay leave should be cooked for just 2 minutes). Cut potatoes into small cubes, put in the saucepan, bring to the boil and cook until soft for 10 min. Remove the stems from the greens. Warm up the remaining oil in a large frying pan, put all the leaves, stir, cover with a lid and cook under a high heat for 3 minutes. Open and stir once again. If all the leaves withered, put the greens into the pot of potatoes and cook under the lid for another 1-2 minutes. Cover eggs for serving with hot water, bring to the boil and cook for 5-6 minutes. Then shower them with cold water and peel. Start heating the soup, bring to the boil and cook for 2-3 minutes. Divide the soup between bowls and put an egg, cut in halves, and a spoon of sour cream in each bowl.